Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C255/00—Carboxylic acid nitriles
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C253/00—Preparation of carboxylic acid nitriles
  • C07C253/14—Preparation of carboxylic acid nitriles by reaction of cyanides with halogen-containing compounds with replacement of halogen atoms by cyano groups

Definitions

• the present invention relates to a process for producing aromatic nitrile and more particularly to a process for efficiently producing aromatic nitriles by reacting aromatic halides substituted by a nitro group in the ortho position relative to the halogen atom with cuprous cyanide and alkali cyanides in an aprotic solvent.
• a method of preparation of aromatic nitriles by reacting aromatic halide and cuprous cyanide is well known as the Rosenmunt von Braun reaction.
• Chemical Abstracts, 59: 6319b describes a method of synthesizing 2-­chloro-6-nitro-benzonitrile by reacting 2,3-­dichloronitrobenzene and cuprous cyanide at a high temperature in a polar solvent, e.g., pyridine or dimethylformamide.
• This method however, needs more than an equimolar amount of cuprous cyanide relative to aromatic halide and further has disadvantages in that the resultant nitrile product forms an insoluble complex with the copper compound, thereby making difficult separation and purification thereof. Moreover, it has a disadvantage in that an operation for removal of copper salts in the product by washing with ammonia water or water is complicated.
• An object of the present invention is to provide a process for producing aromatic nitrile.
• Another object of the present invention is to provide a process for efficiently producing aromatic nitrile using a reduced amount of cuprous cyanide.
• Another object of the present invention is to provide a process for producing aromatic nitrile, in which treatment after the cyanogenation can be easily carried out.
• Still another object of the present invention is to provide a process for producing aromatic nitrile, in which separation and purification of the product are made easier.
• the present invention relates to a process for producing aromatic nitrile which comprises reacting aromatic halide substituted by a nitro group in the ortho position relative to the halogen atom with 0.1 to 0.99 mol of cuprous cyanide per mol of the aromatic halide and 0.1 to 2.0 mol of alkali cyanide per mol of the aromatic halide in the presence of 0.1 to 30 parts by weight of an aprotic solvent per 100 parts by weight of the aromatic halide.
• Various aromatic halides substituted by a nitro group in the ortho position relative to the halogen atom can be used in the present invention.
• compounds represented by the general formula (I) as shown below are used.
• X is a halogen atom
• Z is a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a hydroxyl group or a nitro group
• n is an integer of 1 to 4
• halogen atom represented by X or Z are chlorine, bromine, iodine and fluorine.
• alkyl group having 1 to 4 carbon atoms as represented by Z are a methyl group, an ethyl group, a propyl group, an isobutyl group, a n-butyl group and a tert-butyl group.
• Specific examples of the compound represented by the general formula (I) are 2-chloronitrobenzene, 2-bormonitrobenzene, 2,3-dichloronitrobenzene, 2,4-dichloronitrobenzene, 2,5-dichloronitrobenzene, and 2,6-dichloronitrobenzene.
• the amount of cuprous cyanide used in the reaction with the above aromatic halide is 0.1 to 0.99 mol, preferably 0.2 to 0.5 mol and most preferably 0.3 to 0.4 mol per mol of the aromatic halide. If the amount of cuprous cyanide in the reaction system is less than 0.1 mol, the reaction is retarded. On the other hand, if it is too large, separation of the product becomes difficult.
• the amount of alkalil cyanide used is 0.1 to 2.0 mol, preferably 0.5 to 1.2 mol and most preferably 0.8 to 0.9 mol per mol of the aromatic halide.
• Alkali cyanide which can be used in the present invention include sodium cyanide, potassium cyanide, potassium nickel cyanide, sodium cobalt cyanide, cesium cyanide, potassium dicyanocuprate K[Cu(CN)2] and sodium dicyanocupate Na[Cu(CN)2] .
• both cuprous cyanide and alkali cyanide are reacted with the aromatic halide in the amount ranges specified above.
• the total amount of cyano group of cyanides is 1.0 to 1.4 mol per mol of the aromatic halide.
• the reaction is carried out in the presence of an aprotic solvent, the amount of which is 0.1 to 30 parts by weight per 100 parts by weight of the aromatic halide as a starting material.
• the reaction can be carried out in the presence of an excess amount of the aprotic solvent, for example, in an amount of about 300 parts by weight per 100 parts by weight of the aromatic halide. In this case, however, unless the amount of the aprotic solvent is reduced to 30 parts by weight or less by a technique such as distillation during the reaction or after the completion of the reaction, separation of the product from copper compounds becomes unsuitably difficult for practical use.
• polar solvent there are no special limitations as to the polar solvent to be used in the present invention, and various polar solvents can be used.
• N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N,N′-dimethyl­imidazolidone, dimethylsulfoxide and sulforane can be used.
• reaction conditions are not critical and can be chosen appropriately depending on the circumstances.
• the reaction is usually carried out at a temperature of 100 to 250°C for a period of 2 to 36 hours.
• the product is obtained by the above reaction, i.e., aromatic nitrile is extracted at a temperature of at least 70°C, if necessary, with an organic solvent having a boiling point of at least 70°C.
• Solvents which can be used for the extraction include aromatic compounds, e.g., benzene, toluene, xylene, chlorobenzene, dichlorobenzene and ethylbenzene, aliphatic compounds, e.g., 1,1,2-­trichloroethane, or alicyclic hydrocarbons, e.g., cyclohexane.
• This extraction is carried out under reflux at a temperature of at least 70°C, preferably in the vicinity of the boiling point of the extraction solvent used. At a low temperature less than 70°C, the extraction efficiency is poor, and by carrying out the extraction at a temperature as near as possible to the reaction temperature, the desired product can be effectively separated from the nitrile-copper complex.
• precipitates containing copper compounds are removed by filtration. If the filtrate obtained by the filtration is subjected to post-treatment, such as washing with an alkaline aqueous solution and water, drying and removal of the solvent by the usual method, the desired aromatic nitrile is isolated.
• the precipitate obtained by filtration contains cuprous cyanide, alkali cyanide, copper chloride, alkali metal chloride and their complex salts, a small amount of nitrile-­copper complex, and so on.
• the precipitate is recycled to the reaction system to make good use of the unused cyanide contained in the precipitate, thereby decreasing the amount of cuprous cyanide used in each reaction.
• the precipitate is washed occasionally with water and dried well although it is not always required. If it is not washed with water, salts by-produced during the reaction (e.g., sodium chloride and potassium chloride) accumulate in the precipitate, thereby decreasing the efficiency of operation.
• salts by-produced during the reaction e.g., sodium chloride and potassium chloride
• the precipitate is recycled after drying to prevent side reactions.
• the process of the present invention is effective for preparation of aromatic nitrile which is useful as an intermediate for producing various medicines and industrial organic products and thus can be expected to be used in fields of e.g., organic chemical industry, agricultural chemical industry and medicine producing industry.
• reaction solution was stirred while adding 200 ml of toluene maintained at 120°C in small portions, and extraction was continued at the reflux temperature of the reaction solution.
• the toluene layer was separated, and 100 ml of hot water was added. Separation of the organic layer from the water layer was poor, and the water layer was colored brown and solids were formed therein.
• the organic layer was separated and was subjected to dehydration by adding anhydrous sodium sulfate. Then, 3 g of kaolin was added, and filtration was applied by the use of a filter in which a 5 mm thick kaolin layer was placed. The toluene was distilled away under reduced pressure from the mother liquor thus obtained to obtain 17.5 g (0.092 mol) of CNBN (purity: 96%). The yield based on DCNB was 46.0%.
• the yield based on DCNB was 82.4%.
• the yield based on DCNB was 84.6%.

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• Chemical & Material Sciences (AREA)
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• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Toxicology (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1988
  • 1988-03-19 JP JP63066907A patent/JPH0625097B2/ja not_active Expired - Lifetime
• 1989
  • 1989-03-02 US US07/318,170 patent/US4959487A/en not_active Expired - Fee Related
  • 1989-03-15 EP EP19890104618 patent/EP0334188A3/de not_active Ceased

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